When you work in a medium for long enough, and you learn how it works more and more deeply, you eventually become its master. [Yukio Shinoda] is probably master of the LED bubble display.
She started out with an idea, back in 1994, of a column of water and an array of solenoids to inject air, making patterns in the bubbles. Time passed, and she began to realize these works, first in water and then switching over to glycerine for slower, more predictable, and more spherical bubbles. The latest version realizes her initial vision, after 29 years, with an 8×8 array of nozzles making 3D shapes in the slowly rising columns. Continue reading “Zen And Glowing Air Bubble Displays”→
How many times have you found yourself fumbling about with lighting while trying to get a clear up-close shot of an object? Although smartphones come with pretty nice cameras these days, properly lighting an object and taking impressive macro shots isn’t exactly their strong suit. This is where [MisterHW]’s LEDCard is a very welcome companion. Not only does it provide a credit card sized ring light, it also allows for a molded acrylic lens to be inserted for high-quality macro shots.
The project in its current iteration consists out of a single PCB with rechargeable Li-ion coin cells (LIR2430) and a USB-powered charge controller. After charging the LEDCard (or inserting freshly charged Li-ion coin cells), a single button press will light up the SMD LEDs via the LM3410 LED driver IC. Press the ON button gently (half-press) for medium brightness and fully for full intensity. Finally, pressing the TEST button with the LEDs lit performs a battery level test that turns the LEDs off if the battery is ok. If they stay lit, it’s time to recharge the LEDCard.
As [MisterHW] points out, the LEDCard being compact enough to carry around with you wherever you go makes it suitable as an emergency flashlight as well. It’s also not the final iteration of the design. Future (incremental) improvements include a diffuser for the ring light and more. Even so, in its current state LEDCard is already a proven design.
Infill has an effect on appearance. 20% infill on the left, 100% infill on the right.
For some problems the Goldilocks approach is the way to go. [Tommy] designed a small array of different LED cover options, and tested each to see what yielded the best results for his printed kit. Some of the biggest takeaways include:
100% infill is best for even results (although interesting shadows happen at less than 100% infill.)
Interesting things happen with 7 to 11 mm of top layers of clear PLA, when illuminated from below with a 5 mm high-brightness LED. An even diffusion of light starts to give way to a circular gradient as the upper layer gets thicker.
LEDs emit their light mainly upward in a round pattern. Corners will always be darker, even more so if the guide is not round. This effect becomes noticeably more pronounced as the light guide grows in size, putting a practical upper limit on its effective dimensions.
Of course, the usual ways to deal with an overly-bright LED are to limit its current or control its brightness by driving it with a PWM signal. The right approach depends on the application and the scale of the design, and there are actually quite a few ways to crack this nut. Luckily, our own [Inderpreet Singh] is here to tell you all about how best to control LED brightness.
The program is known as TwinkleFOX, and relies on the popular FastLED library for addressable LEDs. [Mark’s] demo setup is built around using WS2811 LEDs, put together in a string with plastic diffusers on each bulb. The Arduino is programmed to vary the brightness of each LED according to a triangle wave function. To create the twinkling effect, each LED has its own unique clock signal, so they vary in brightness at different times and at different rates.
Using an Arduino Uno or Leonardo, [Mark] reports its possible to twinkle 300 individual LEDs at a rate of over 50 updates a second. Using a faster microcontroller should net reliable performance with longer strings. Meanwhile, if you’re wondering how the older-style lights used to twinkle, we’ve covered that before too. Video after the break.
Traveling by bicycle can be a fun and exciting mode of transportation, and can also save a ton of money compared to driving a car. There are plenty of places around the world where a bicycle is the primary mode of transportation for a significant percentage of the population, but there are many more places that are designed entirely for cars with little thought given to anyone else. For anyone riding a bike, especially for people living in these car-dominated areas, additional safety measures like this LED array are often necessary.
The light array was created by [Estudio Roble] for traveling around his city. The design is based on the Adafruit Circuit Playground Express, which sits directly in the middle of the light fixture. Surrounding it is a diamond-shaped strip of LEDs within an additional ring. The light uses a bright blue color for normal driving, but is programmed to turn red when the accelerometer in the dev board detects braking. There are also integrated turn signals which operate similarly to motorcycle turn signals. The signal is sent wirelessly between the handlebar switch to the lights.
The device itself clips onto any backpack, and since the controller is wireless there are no wires to connect every time a rider gets on their bike. It’s quite an improvement over the complete lack of lighting on most bikes. If you’ve read this far, you need to check out this bicycle headlight which uses a projector to display information directly in the path of travel.
There was a time when LED light bulbs were a premium product that commanded a premium price, mainly because of limited supply and the usual marketing tricks. But now is not that time, since you can pick up an LED bulb for a buck or two at pretty much any store. So why in the world would you go to the effort to make your own light bulb?
For [DiodeGoneWild], the answer is simple: it’s all about staying in rhythm. Circadian rhythm, that is. We all know how light toward the blue end of the spectrum is bad for our sleep cycle, since it convinces our lizard brain that dawn is at hand. But even if you pick an LED bulb with a warm, or reddish, color temperature, there’s still a lot of UV light being emitted thanks to the phosphor LEDs that are typically used in them.
[DiodeGoneWild]’s first attempt at a design, in the first video below, mostly avoids phosphor LEDs in favor of a mix of yellow, red, and yellow-green LEDs to get a warmer spectrum. He used the housing and base from an expired bulb to enclose his custom circular PCB, the fabrication of which using a hand drill as a lathe and a Dremel to machine concentric tracks in the cladding was a real treat. So was the power supply, for that matter — a dropping capacitor followed by a bridge rectifier and a filtering cap. We like the discharge resistors across the caps and the fusible resistor on the mains side — it’s nice to see safety factored in from the start. And what’s not to like about using a DVD as a makeshift spectroscope?
We see that [DiodeGoneWild] has just dropped a second design, this time in a much smaller bulb and with relatively more phosphor LEDs.
Chinese Youtuber [corebb] presents the second version of his POV display. The earlier version used 5050-sized SMT addressable LEDs, which didn’t give great resolution, so he rev’d the design to use a much higher number (160 to be exact) of APA102 LEDs. These are 2mm on the side, making them a little more difficult to handle, so after some initial solder paste wobbles, he decided to use a contract assembly house to do the tricky bit for him. This failed as they didn’t ‘understand’ the part and placed them the wrong way around! Not to be deterred, he had another go with a modified solder stencil, and eventually got the full strip to light up correctly.
Based on an ESP32 (using the Arduino stack) and SDCard for control, and a LiPo cell charged wirelessly, the build is rather tidy. A couple of hall effect switches are mounted at the start of each of the two arms, presumably lining
Real-time video streaming? Check!
up with a magnet on the case somewhere, although this isn’t clear. The schematic and PCB appear to have been designed with JLCEDA, which is a repackaging of EasyEDA. We can see the attraction with the heavy integration of this with the JLC and LCSC services. It appears that he even managed to get streamed video working — showing a live video from a webcam — which is quite an undertaking to pull off when you think how much processing needs to happen in real-time. As he alludes to in the video, trying to increase the resolution beyond this point is not viable with the processing capability of the ESP32.
A resin-printed case finishes off the build, with a screw-thread mount added to the rear, to allow typical camera mounts to be used to hold the thing down. A smart move we think.
The program is known as TwinkleFOX, and relies on the popular 
